They are also highly soluble.

Take gypsum crust from the dry cave wall and expose it to rain or humidity, and it will dissolve.

This is why archaeologists faced such a fundamental challenge in understanding the mineral economy of the ancient miners: the materials they collected, once removed from the cave and taken into the outdoor world, do not survive.

No caches of cave gypsum have been found at ancient habitation sites.

No storage vessels have been identified that clearly held these minerals.